In spectral analysis a beam of light is applied to an instrument which spreads the light into a spectrum angling the light at angles which are a function of the wavelength. The thus spread light is detected at points to be able to identify the light peaks or more complete the intensity versus wavelength and thus determine the spectrum and its associated source characteristics.
Present day resolution needs require spectral analysis of high resolution and positional accuracy. This in turn requires more linearity, calibration accuracy and optical resolving power than is available in present day instrumentation.